This application is for a Biacore 2000 Instrument to be located at the Public Health Research Institute. A group of five principal investigators, all of whom are recipients of NIH grants, will comprise the major user group. In addition, minor users both inside and outside the Institute will have access to the instrument on a selective basis. The projects to which the Biacore instrument will be applied are varied in nature. Two of them (Drs. Pinter and Tilley) are HIV -related. Dr. Pinter is concerned with vaccine development and will use SPR to explore the affinities of various monoclonals to defined epitopes in the V1/V2 domain. Dr. Tilley will use the instrument to study the reactivities of monoclonals, and seropositive sera with HIV-1 envelope glycoproteins and epitopes thereof. Dr. Penetsky will use SPR to explore the assembly of the F1/F0 ATPase. Dr. Dubnau will use the Biacore 2000 to study a variety of protein-protein and protein-DNA interactions involved in the regulation of competence development and the uptake of transforming DNA by competent bacteria. Dr. Pine will explore the influence of M. tuberculosis infection of macrophages on the DNA-binding activities of several transcription factors.